Java 休眠未保存的子对象
我有一个Employee和Employee Dept表。一名员工可以有多个部门 我在MySQL中定义了表,并使用JPA生成了实体Java 休眠未保存的子对象,java,mysql,hibernate,Java,Mysql,Hibernate,我有一个Employee和Employee Dept表。一名员工可以有多个部门 我在MySQL中定义了表,并使用JPA生成了实体 package model; import java.io.Serializable; import javax.persistence.*; import java.util.List; /** * The persistent class for the emp1000 database table. * */ @Entity @NamedQuery
package model;
import java.io.Serializable;
import javax.persistence.*;
import java.util.List;
/**
* The persistent class for the emp1000 database table.
*
*/
@Entity
@NamedQuery(name="Emp1000.findAll", query="SELECT e FROM Emp1000 e")
public class Emp1000 implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private String firstName;
private String lastName;
//bi-directional many-to-one association to EmpDept
@OneToMany(mappedBy="emp1000")
private List<EmpDept> empDepts;
public Emp1000() {
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public String getFirstName() {
return this.firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return this.lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public List<EmpDept> getEmpDepts() {
return this.empDepts;
}
public void setEmpDepts(List<EmpDept> empDepts) {
this.empDepts = empDepts;
}
public EmpDept addEmpDept(EmpDept empDept) {
getEmpDepts().add(empDept);
empDept.setEmp1000(this);
return empDept;
}
public EmpDept removeEmpDept(EmpDept empDept) {
getEmpDepts().remove(empDept);
empDept.setEmp1000(null);
return empDept;
}
}
@Entity
@Table(name="emp_dept")
@NamedQuery(name="EmpDept.findAll", query="SELECT e FROM EmpDept e")
public class EmpDept implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
@Column(name="emp_dept")
private String empDept;
//bi-directional many-to-one association to Emp1000
@ManyToOne
@JoinColumn(name="emp_id")
private Emp1000 emp1000;
public EmpDept() {
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public String getEmpDept() {
return this.empDept;
}
public void setEmpDept(String empDept) {
this.empDept = empDept;
}
public Emp1000 getEmp1000() {
return this.emp1000;
}
public void setEmp1000(Emp1000 emp1000) {
this.emp1000 = emp1000;
}
}
您需要将持久化操作级联到子实体。将映射更改为
@OneToMany(mappedBy="emp1000", cascade = CascadeType.ALL)
使用
如果我们同时使用hibernate和jpa,而不是使用javax.persistence.CascadeType.ALL,则会出现一个问题。我尝试过,但出现了一个错误。。鉴于上述帖子中的错误,
emp#u部门id
列的数据库类型是什么?我将列类型更改为id
int(11)NOT NULL AUTO#u INCREMENT,即;添加了AUTO_INCREMENT并开始工作…谢谢这就是为什么我问你,AUTO_INCREMENT
应该已经存在了,如果你让Hibernate自动生成表的话。不客气,很高兴您能让它工作。还有一个问题..我是否需要显式设置部门对象d1.setEmp1000(e1),即使这些部门与该员工相关-e1.setEmpDepts(deptlist);
Feb 25, 2015 8:43:43 AM org.hibernate.util.JDBCExceptionReporter logExceptions
SEVERE: Field 'id' doesn't have a default value
Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not insert: [model.EmpDept]
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91)
@OneToMany(mappedBy="emp1000", cascade = CascadeType.ALL)
@Cascade({org.hibernate.annotations.CascadeType.ALL})